智能合约dapp**技术主要由以太坊***网络提供支持，该网络提供了一系列的智能合约技术，这些智能合约可以让**者快速、安全地构建出功能强大的dapp。智能合约dapp**技术主要包括以太坊智能合约语言Solidity，以太坊智能合约框架Truffle，Web3.js，以太坊***浏览器Mist等
智能合约：它们是存储在***上的计算机程序，在满足预定条件时运行，智能合约是用Solidity语言编写的。
web3.js是一个JavaScriptAPI库。要让DApp在以太坊上运行，我们系统-176搭建-0206+可电可微-5616可以使用web3.js库提供的web3对象。web3.js通过RPC调用与本地节点通信，它可以与任何公开RPC层的以太坊节点一起使用。web3包含eth对象-web3.eth（用于与以太坊***交互）和shh对象-web3.shh（用于与Whisper交互）
//this low-level function should be called from a contract whichperforms important safety checks
function burn(address to)external lock returns(uint amount0,uintamount1){
(uint112 _reserve0,uint112 _reserve1,)=getReserves();//gassavings
address _token0=token0;//gas savings
address _token1=token1;//gas savings
uint balance0=IERC20(_token0).balanceOf(address(this));
**功能176详情0206系统5616
uint balance1=IERC20(_token1).balanceOf(address(this));
uint li=balanceOf[address(this)];
bool feeOn=_mintFee(_reserve0,_reserve1);
uint _totalSupply=totalSupply;//gas savings,must be defined heresince totalSupply can update in _mintFee
amount0=li.mul(balance0)/_totalSupply;//using balancesensures pro-rata distribution
amount1=li.mul(balance1)/_totalSupply;//using balancesensures pro-rata distribution
require(amount0>0&&amount1>0,'UniswapV2:INSUFFICIENT_LI');
_burn(address(this),li);
_safeTransfer(_token0,to,amount0);
_safeTransfer(_token1,to,amount1);
balance0=IERC20(_token0).balanceOf(address(this));
balance1=IERC20(_token1).balanceOf(address(this));
_update(balance0,balance1,_reserve0,_reserve1);
if(feeOn)kLast=uint(reserve0).mul(reserve1);//reserve0 andreserve1 are up-to-date
emit Burn(msg.sender,amount0,amount1,to);
}
function swap(uint amount0Out,uint amount1Out,address to,bytescalldata data)external lock{
require(amount0Out>0||amount1Out>0,'UniswapV2:INSUFFICIENT_OUTPUT_AMOUNT');
require(amount0Out<_reserve0&&amount1Out<_reserve1,'UniswapV2:INSUFFICIENT_LI');
uint balance0;
uint balance1;
{//scope for _token{0,1},avoids stack too deep errors
address _token0=token0;
address _token1=token1;
require(to!=_token0&&to!=_token1,'UniswapV2:INVALID_TO');
if(amount0Out>0)_safeTransfer(_token0,to,amount0Out);//optimisticallytransfer tokens
if(amount1Out>0)_safeTransfer(_token1,to,amount1Out);//optimisticallytransfer tokens
if(data.length>0)IUniswapV2Callee(to).uniswapV2Call(msg.sender,amount0Out,amount1Out,data);
}
uintamount0In=balance0>_reserve0-amount0Out?balance0-(_reserve0-amount0Out):0;
uintamount1In=balance1>_reserve1-amount1Out?balance1-(_reserve1-amount1Out):0;
require(amount0In>0||amount1In>0,'UniswapV2:INSUFFICIENT_INPUT_AMOUNT');
{//scope for reserve{0,1}Adjusted,avoids stack too deeperrors
uintbalance0Adjusted=balance0.mul(1000).sub(amount0In.mul(3));
uintbalance1Adjusted=balance1.mul(1000).sub(amount1In.mul(3));
require(balance0Adjusted.mul(balance1Adjusted)>=uint(_reserve0).mul(_reserve1).mul(1000**2),'UniswapV2:K');
